Multiplex alternating-current telegraphy



18 1927. Oct J. VOPEL MULTIPLEX ALTERNATING CURRENT TELEGRAPHY FiledSept. 15. 1924 Patented 18, 1927.

UNITED STATES PATENT- OFFICE.

JOEAINEB VOPEL, OF IBERLIN-HABIENDOBF, GERMANY, ASSIGNOR TO LORENZAKTIENGESELLSOHAIT, BEBLIN-TEMPELHOF, GERMANY.

KULTI'PLEX ALTIERNA'LING-(JURIREN''1 TELEGRAIPHYZ.

Application filed September 15, 1924, Qerial No. 737,766, and in GermanySeptember 24, 1923.

My invention relates to improvements in multiplex telegraphy in whichthe synchronous transmission of several messages over one wire iseflected by means of alternating currents of difierent frequencies. Thesystem of multiplex telegraphy referred to acts by transmitting aplurality of alterating currents of different frequencies and each carrying a different message over one transmisslon line. from one terminaltelegra h station to another associated station, while commutators areprovided at this latter sta tion connected between said transmissionline and a plurality of terminal telegraph circuits each one of whichcorresponds to one of the above mentioned alternating telegraphingcurrents. The commutators operate in synchronism with each of theirrespective telegraphing currents in such a manner as to convert thereceived alternating currents into direct current-telegraph impulses.

The ran e of alternating current freuencies to is used for multiplextelegraphy epends essentially on the quality of the wine used. Thenumber of messages to be transmitted for a certain range of frequenoiesdepends on the selectivity of the receivin apparatus to be employed andon the to egraphing speed. According to my invention in a system ofmultiplex telegraphy of the kind referred to there are employed\ twoalternating currents of the same fre uen but with a phase difference of90 g or t e simultaneous transmission of two 85 diflFerent messages,whereby the number of messages to be transmitted for a certain '-rangeof frequencies may be doubled. Hence for simultaneously transmitting twotelegrams two different frequencies are not 40 required as heretofore,but only'two alternating currents of the same frequency but having aphase displacement with respect to one another of 90. If on thetransmitting side there is therefore employed an alternator suitablyconstructed or connected for this pu ose,the. two alternating currentsdispl by 90 can be separated by two commutators at the receiving stationso arranged'as to have a relative phase displace W ment with respect toone another of 90, or by one single commutator having two sets ofbrushes displaced by 90 with respect to one another.

In multiplex systems of similar type to that previously referred tobutusing resonating circuits for separating the different frequencies,telegraphic signs can only be transmitted by switching in orinterrupting the alternating current, while according to a furtherfeature of my invention when using synchronously'operated commutatorsinthe, 7 known manner hereinbefore mentioned separable current can beused, for instance in such a way that at the end of every telegraphicsign the phase of the alternating current is changed by 180, whiclr actson the relay behind thmcommutato'r'of the receiving-system as a currentopposite to the current of the signs, thus enabling a neutral relay tobe. employed. This reversal of the current by 180? can be attained bysimply changing the polarity of the terminals of the line with theposition of the key, or by employing a potentiometer across theterminals of the current generator, one pole of the transmission linebeing connected to a tapping point in the center of the potentiolneterso that when operating the key either the one or the other terminal ofthe potentiometer is connected to the other pole of the line, or arepeater having a transformer ratio of 1:1 may be em loyed the primaryor secondary of which is alterna- "tively connected to the lineaccording to the position of the key. 1

In order that the invention may be clearly understoodand readily carriedinto efi'ect i the same will now be described'more fully with referenceto the accompanying drawings in which c i Figure 1 illustratesdiagrammatically the electrical connections of the system of telegraphyreferre'dto, and Figures 2 and 3 are curves representing the transmittedand commutated currents obtained in the various methods of operationaccording to the present invention. Referring to Figur 1, T T and T arekeys each ofwhich is connected to one of three sources of alternatingcurrent of dif ferent frequencies and by means of which the first,second and third frequencies F F F respectively can be tapped andtransmitted along the line wire L by the common coupling relay A. Forseparating the car rying frequencies, there are provided rotatingcommutators K K K coupled to the main line at A in a similar way as thenerators at the transmitting station.

ach commutator is constructed so as to 110 commutate the alternatingcurrent of one particular frequency, so that the commutetor K commutatesthe frequency F but does not ccmmutate the frequencies F and F The relaydevice R, is therefore actuated only by its own corresponding carryingfrequency F The commutators K and K and their respective relay devicesR, and R are each operated in a like manner. The receiving commutators KK, and K may be driven by one motor for instance, acting synchronouslyand in phase with a multiwave alternator of the sending system pro--during the different signalling frequencies.

Referring to Figure 2 curve a shows the current sent along the wire whenthe sign is given and curve a the resulting commutated current in thereceiving system. Curve 5 shows how during a spacing interval the phaseof the alternating current sent along the wire is displaced by 180 aspreviously stated and curve (1 shows how at the same time thecomrhutated current of the receiver changes its direction. Figure 3illustrates the method of operation employing two currents of the samefrequency but displaced with respect one to another by 90; F is thealternating current sent along the wire, f the same current commutatedby a commutator in phase, i the current commutated by a commutatordisplaced in phase by 90. The resulting direct current of every halfperiod being zero, f does not act upon the receiving device.

What'I claim and desire to secure by Letters Patent of the United Statesis as follows:

1. In a system for simultaneously transmitting several messages over oneconnecting line by means of two alternating currents of equal frequencyand phase displacement of 90 with respect to each other and forseparating these currents in the receiving" station, the combination ofa mechanical commutating device in the receiving systemfor eachsignaling current transmitted and means to operate said commutating.devices synchrononslyand in like phase relationship with the transmitterat the sending system generating the respective signaling currents, saidcommutating devices being so arranged as to commutate only their ownparticular signaling current.

2. In a system for transmitting simultaneous'ly several messages overone connecting line by means of pairs of alternating cur rents of equalfrequency and phase displacement of 90 with respect to each other, eachpair being of a difierent frequency, and for separatin these currents inthe receiving. system, 1; e combination of a mechanica messescommutating device in the receivingsystem for each signaling currenttransmitted and means to operate said commutating devices synchronouslyand in like phase relationship with the transmitter at the sendingsystem generating the respective signaling currents, said commutatingdevices being so arranged as to commutate only their own particularsignaling current.

3. In a system for simultaneously trans-- mitting several messages overone connecting line, the combination of a number of generators at thesending system for producing pairs of signaling alternatin currents,each two currents of each of sai pairs being of equal frequency anddisplacement by 90 with respect to each other, a trans-.

mission line connecting said sending enerators with a receiving system,mec anical commutators at said receiving System, and I means to operatesaidcommutators in synchronism and in like relationship with one of saidgenerators at said sending system, said commutators being arranged tocomma tate only their own particular signaling current.

' 4. In a system as claimed in claim 1,, in which in the pauses of si nsalternating current with phase displaced by 180 is sent by thetransmitting system over the conduct ing wire and a current opposite tothat produced by the signs is generated in the receiving system behindthe commutator, twodifi'erent messages being simultaneously transmittedby the employment of two alternating currents of the same frequency, butwith a phase difference of the two commutators in the receiving systemhaving a relative phase displacement with respect to one another of 90so as to separate the-two alternating currents differing in phase by 90sent out by the transmitter.

5 In a system as claimed in claim 2, in which in the pauses of signsalternating current with phase displaced by 180 is sent by thetransmitting system over the conducting wire and a current opposite tothat produced by the slgns is generated in the receiving system behindthe commutator, two different messages being simultaneously transmittedby the employment of two alternating currents of the same frequency, butwith a phase difference of 90, the two commutators in the receivingsystem having a relative phase displacement with respect to one anotherof 90 so as to separate the two alternating currents differing in phaseby 90 sent out by the transmitter.

In testimony whereby I have affixed my

